Aerosol insecticidal compositions are well known. For example, U.S. Pat. No. 3,524,911 (to Leavitt) teaches such compositions. The Leavitt compositions are said to form a self-sustaining, relatively rigid insecticide-containing foam which, the patent discloses, is able to persist for prolonged periods of time. The aerosol-spray compositions disclosed in the Leavitt patent, which compositions are characterized as comprising an essentially nonaqueous mixture, are insoluble in water.
The insecticidal compositions disclosed herein, in contradistinction to the insecticidal compositions disclosed in the Leavitt patent, are water soluble.
British Pat. No. 1,107,140 (to Mitchell et al.) discloses an aerosol-dispensed, insecticide composition which is applied as a spray, not a foam. This British patent, in fact, teaches away from the production of a foam. More particularly, Mitchell et al. teaches producing a mist which is designed to remain air-borne for a desired period of time. (One such air-borne type insecticide is referred to in the art as a "flying insect killer" or FIK type insecticide.) Whereas the instant invention is specifically designed and adapted to be applied onto a surface, and into cavities, crevices and the like.
In the area of insect control, it is desirable to be able to present a positive barrier to insects, such a barrier being generally not providable by an air spray-type of application.
In the related area of rodent control, U.S. Pat. No. 3,816,610 (to Lusby) discloses a palatable rodent-control material that can be formed-in-place and used, for example, to fill holes through which the rodents are accustomed to run. The foam, disclosed in the Lusby patent, is said to be able to expand in volume to fill up a cavity, taking the shape thereof and thereafter becoming rigid. The plastic foam cellular structures disclosed in the Lusby patent, while useful for one purpose, because they become rigid and are insoluble in water, unfortunately cannot readily be removed from many cavities into which they are formed-in-place.
Yet, in the area of insect control it is desirable not only to prevent a positive insect barrier in, for example, cracks and crevices, beneath doors and around windows, and in drain pipes from fixtures such as sinks and tubs, it is also desirable to present such a positive insect barrier that is readily removable, when desired.
Also related to the area of insect control is U.S. Pat. No. 3,970,584 (to Hart et al.), which discloses, in addition to a variety of foam compositions, a foam-forming insect repellent composition. More particularly, the insect repellent compositions disclosed in the Hart et al. patent are referred to in the art as "personal care" products (i.e., lotions, skin creams and the like) which, upon application, generally either form thin films on or are absorbed into the skin. Whereas the present invention is directed to a positive insect barrier.
While insect repellents function by repelling insects away from a situs, many insecticidally-active substances function by drawing insects toward a situs for the purpose of causing death upon contact with an insect toxicant-containing substance.
Another notable difference between the present invention and the Hart et al. patent is that the Hart et al. patent teaches that its insect-repellent composition requires a complex propellant system consisting essentially of nitrous oxide and isobutane, which propellant system, the Hart et al. patent teaches, must be present in specified quantities, to achieve the stated objects of the Hart et al. patent. In contradistinction, the present invention has no such complex propellant-system requirement, and any suitable propellant can be utilized.
Accordingly, a foamable, insecticidally-active composition, not dependent upon a complex propellant system to produce a foam, wherein the foam is able to expand to substantially fill a cavity, and wherein the foam is water-soluble so as to be readily removable (from the cavity) when desired, is presently in demand and of commercial significance.
The instant invention is thus distinguishable from prior art discussed above in that the foamable water-soluble insecticidally-active composition disclosed herein is able to produce an expandable foam capable not only of substantially filling a cavity (in place) but also of existing in a stable form in the cavity for hours or weeks (depending upon, inter alia, water content of the composition, the amount and type of surfactant or foaming agent in the composition, and the quantity and type of propellant that is utilized).